What's New in iSCSI Target Server in Windows Server

Updated: July 3, 2014

Applies To: Windows Server 2012 R2

This topic describes the new and changed functionality of iSCSI Target Server in Windows Server 2012 R2.

iSCSI Target Server enables you to network boot multiple computers from a single operating system image that is stored in a centralized location. This improves efficiency, manageability, availability, and security. iSCSI Target Server can boot hundreds of computers by using a single operating system image. Other scenarios in which you can use iSCSI Target Server include:

Some server applications require block storage, and iSCSI Target Server can provide these applications with continuously available block storage. Because the storage is remotely accessible, it can also consolidate block storage for central and branch office locations.

When iSCSI Target Server is enabled, a computer running the Windows Server operating system becomes a network-accessible block storage device. This is useful for testing applications prior to deployment in a storage area network (SAN).

The following table lists functionality in iSCSI Target Server that is new or has been changed for this release.

Feature/functionality

New/updated

Summary

Virtual disks enhancements

New

Includes a redesigned data persistence layer that is based on a new version of the VHD format called VHDX (VHD 2.0). VHDX has a much larger storage capacity than the older VHD format. iSCSI Target Server also provides data corruption protection during power failures and optimizes structural alignments of dynamic and differencing disks to prevent performance degradation on new, large-sector physical disks. You can still import VHD 1.0 disks by using Windows Server 2012 R2.

iSCSI Target Server now sets the disk cache bypass flag on a hosting disk I/O, through Force Unit Access (FUA), only when the issuing initiator explicitly requests it. This change can potentially improve performance. Previously, iSCSI Target Server would always set the disk cache bypass flag on all I/O’s. System cache bypass functionality remains unchanged in iSCSI Target Server; for instance, the file system cache on the target server is always bypassed.

Scalability limits

Updated

Increases the maximum number of sessions per target server to 544, and increases the maximum number of logical units per target server to 256.

Local mount functionality

Updated

Deprecates local mount functionality for snapshots. As a workaround, you can use the local iSCSI initiator on the target server computer (this is also called the loopback initiator) to access the exported snapshots.